Electrical musical instrument



Filed July 30, 1932 4 Sheets-Sheet 1 INVENTOR BY Mbfiobs [anger ATTORNEYMarch 12, 1935. N. LANGER 1,993,390

I ELECTRICAL MUSICAL INSTRUMENT Filed July 30. 1932 4 Sheets-Sheet 2 i51H gjJ-z gjJ-a giJ-rii-isg Jr;

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INVENTOR I BY Mk'fiobs [anger Qvm ATTORNEY March 12, 1935.

N. LANGER 1,993,890 ELECTRICAL MUSICAL INSTRUMENT Filed July 50, 1932 4s t -s 3 B I III l'l,l

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Ml'fialas Luger FIGJZ. a Gym ATTORNEY Patented Mar. 12, 1935 PATENTOFFICE ELECTRICAL MUSICAL INSTRUMENT Nicholas Langer, Budapest, Hungary,asslgnor oi sixty-six and two-thirds per cent to John Halmm], Budapest,Hungary Application July 30, 1932, Serial No. 626,456

12 Claims.

The present invention relates to an improved electrical musicalinstrument of the type in which sounds are produced by means ofelectrical oscillations artificially established in circuits containingglow-discharge lamril}? It is an object of the present invention toprovide an improved electrical'musical instrument of the type describedhereinabove embodying a plurality of keys connected to resistances whichare, connected in series.

'It is the further object oi the present invention to produce andimitate sound effects characteristic of known musical instruments usingstrings, reeds and other mechanically vibrating members and to producemusic which simulates that produced by any of the aforesaid instruments.

It is another object of the invention to produce electrical oscillationsof a very constant frequency and of an even volume throughout the entiremusical range, which oscillations are especially adapted to be convertedinto musical sounds.

It is also within the contemplation of the invention to provide aninstrument capable of coacting with electrical amplifiers of thethermionic type and ordinary radio sets to give the necessary or desiredvolume.

Other objects and advantages of the invention will become apparent fromthe following description taken in conjunction with accompanyingdrawings in which;-

Fig. 1 is a diagrammatic view depicting a complete circuit of anelectrical musical instrument embodying the present invention;

Fig. 2 is a view similar to Fig. 1 showing an embodiment of my improvedelectrical musical instrument in which every note can be tunedindependently ofthe others;

Fig. 3 shows a device for imitating the vibrational eilectcharacteristic of string instruments and the human voice;

Fig. 4 illustrates an electric circuit for obtaining the same imitationof the vibrational effect by an automatic electrical arrangement;

Fig. 5 is a circuit for producing an imitation of the quality ofinstruments in which the strings are plucked as in the banjo, mandolin,etc.;

Figs. 6 and 7 are fragmentary sectional views of a control device, whichis the part of the instrument in Fig. 1 which permits a simultaneouscontrol of volume and of either the tremolo or banjo eflect with onlyone hand of an operator;

Fig. 8 is an electric circuit showing the trans fer of the electricaloscillations set up in my electrical instrument to a thermionicamplifier by means of a photo electric cell without any wire connection;

Fig. 9 illustrates an electric circuit and arrangement for imitating thetone quality of a piano; 5

Fig. 10 is an electric circuit for producing several tone qualitiessimultaneously with the aid of only one glow-discharge lamp;

Fig. 11 is a diagrammatic view of a glowdischarge tube with a shield;and 10 Fig. 12 is a schematic view of a modified circuit. Referring moreparticularly to Fig. l a circuit of my improved electrical musicalinstrument is shown which permits the production of a great variety oftone efiects. For example, a great number of notes of difierent pitch, avariation of the quality of tone, a close imitation of banjo andmandolin effects, a true vibrato and eflicient control of the volume canbe obtained.

For the sake of simplicity and clarity only one glow-discharge lamp isshown in the circuit, so that only one note of musical frequency can beproduced at a time. Obviously a multiplicity of such circuits can bearranged to cause the production of several musical notessimultaneously. In this case, of course, a number of the elements orparts of the circuits can be common, as, for instance, the battery, theoutput transformer, the volume and tone control, etc., as one skilled inthe art will readily understand. 30

Essentially the electric circuit consists of a current source B, aglow-discharge lamp G, a variable condenser C-l; the transformer T andfixed resistors R-l to 13-1: which can be connected by means of keys K1to K--n across 35 C-l. For convenience this part of the circuit, whichwill be hereinafter called the main circuit, is indicated in thedrawings by thicker lines.

Resistances R1 to R-n are all in series and one or any number of themcan be connected across condenser C1 by operating the corresponding key.When. in this manner, one or more resistors are connected acrosscondenser C1, oscillations will be produced, the frequency of whichdepends on the capacity of 0-1, the resistance connected across C1 bythe operated key, and the electromotive force of the current source B.By choosing suitable values for these factors it is possible to produceany musical frequency desired. For instance, an electromotive force ofabout volts, a condenser C1 of about 0.001 microfarads and a resistanceR1 of about 1 megohm will produce an oscillation of about 5/600 of asecond. By giving suitable 55 .is very likely that all the though thereare only five resistors depicted in- Fig. 1, any number of them can beconnected in series up to say about 40 to 50 or more. Approximate valuesfor the resistances in this case are R1 equals 1,000,000 ohms, R-2equals 70,000 ohms, R3 equals 75,000 ohms, R-4 equals 78,000 ohms, R-5equals 84,000 ohms, etc. The advantage of having all theresistors inseries is easily understood from the consideration that the proportionof the frequencies produced by the keys depends only on the proportionof the resistor values as those skilled in the art will. readilyappreciate. Changes in the capacity of (2-1 or in the voltage of currentsource B, will aflect every note in the same degree so that all of themmay become higher or lower, but their relation to each other will alwaysremain the same. In other words, the instrument will stay in tune. Thisapplies also to the case when the resistors increase or decrease inresistance due to ageing, temperature differences and the like, becauseit resistors of thesame make and construction will be affected in thesame way.

It is to be noted that another important advan tage of the describedseries arrangement of the resistors that in case there are several keysdepressed at the same time, only the note of the highest pitch will beheard because if, for in stance, K-1 and K-3 are depressedsimultaneously only R.1 will be connected across C--l, while R-2 and R-3are short circuited and will not influence the pitch of the oscillationsproduced. This makes it possible for the operator to rest his fingers onthe keys, or in case an inexperienced operator happens to strike two ormore keys at the same time no irrational notes will be produced but onlythe note corresponding to the highest key depressed. A further ad:-vantage is that by having one finger resting on a. key and by depressinga higher key with another finger in rapid succession, the two notes canbe produced so quickly after each other that they give the impression ofbeing heard simultaneously. Although at any particular -moment only onenote is being emitted, polyphonic music has been successfully imitatedby my improved electrical instrument. In passing it is to be observedthat the oscillations produced are transferred by means of thetransformer T to a thermionic amplifier and then to a sound producingcontrivance L. The other parts of the circuit serve for adlusting thequality (color), pitch, and finally the volume of the oscillationsproduced.

Referring to the supplementary parts of the electrical circuits, apotentiometer P-1 shunted across part of the current source makes itpossible to change the electromotive force in the circuit and thus thepitch of the oscillations established by the operation of any of thekeys.

The same effect can be obtained by varying 0-1, but the changing of theelectromotive force has the very important advantage that all the notesalong the whole range are aifected in the same degree and the relativeproportion of the frequencies remains unchanged. This enables theoperator to transpose a melody into any musical key desired by simplyturning the potentiometer P-1, which is a very important advantage fromthe musical point of view. The various posiharmonics.

tions of the potentiometer raise or lower the pitch of every note of theinstrument a certain fixed amount (octave, fifth, third, etc.) which can.be marked and thus ,add to the usefulness of the instrument.

The known vibrato or tremolo effect of string instruments consists inslight periodical variations of the pitch imitating the vibrato of thehuman voice. A small capacity C--2 can be intermit- 'tently added to C-lby moving the control lever A to and fro and alternately closing contact(1-1. In this case the desired small variations of frequency areobtained by small changes of the capacity in the circuit, but, ofcourse, the same effect can be obtained by varying the resistance or theelectromotive force in the circuit, either by hand, or automatically. Afew other methods for producing the aforesaid eifect will be describedhereinafter.

The same control lever A is used'for producing an imitation of the tonequality of a banjo or mandolin. In order to produce this effect referredto in the following as banjo or mandolin effect, a switch S--1 is putinto the right side position. In this case the contacts d,--l and (1-2will be connected to each other and the main circuit will be interruptedat d'-3 and is completed only when lever A makes contact with (iv-"l ord-Z.

in other words when any one of the keys will be depressed this fact initself will not produce any oscillations unless the circuit is completedat (I -l or d-2 by moving the lever A to the left and the right. At anyinterruption a little ciick will be heard in the speaker, and this withthe interruptions of the note will give a striking imitation of amandolin or banjo according to the circumstances, whether the originalquality is rich or poor in the higher harmonics. Obviously the sameeffect can be obtained by interrupting the main circuit at other pointseither by hand or by some kind of automatic mechanical interrupter,buzzer, etc.

The original quality obtained by the glow-discharge lamp oscillator isvery rich in the higher Many other different tone colors containing moreor less of the higher harmonics can be obtained by connectingcapacities, resistors or inductances across a suitable part of thecircuit as for instance across the primary of the output transformer aby-pass condenser offering less resistance to the higher frequenciesproduces a mellow, flute-like quality, whereas resistors or inductanceshave the tendency of distorting the oscillations and producing higherfrequencies. A switch 8-4 can be used forconnecting alternately a numberof different organs, condensers and inductances (0-3 and L) across theprimary of the transformer and to produce different qualities. Thevolume of the output is controlled by a high resistance potentiometerP--2, connected advantageously across the secondary of the outputtransformer, so that the resistance. variations while varying the volumedo not affect the impedance of the main (primary) circuit and thus thepitch of the oscillations produced. The same control lever can be usedfor controlling the volume, and to produce either the tremolo or banioefl'ect simultaneously. A more detailed view of this combined controldevice can be seen in Pig. 5, the method of connections being the sameas shown in Fig. 1.

The control lever A can be moved in a slot in two directionsperpendicular to each other. The movement in the first direction, in theplane of the drawing, moves a sliding arm E on the potentiment withfixed tuning. This means that alometer P-2 and varies the volume. It isto be noted that the control lever A consists of two parts insulated atO, the upper part being made out of a flexible material, such as a flatstrip of spring steel which permits little movement of the leverperpendicular to the former, and which makes contact alternately withd-l and 11-2. This design makes it possible for the operator to controlthe volume of the oscillations by moving lever A in the slot and toproduce at the same time the vibrato or the banjo effect according tothe position of 8-1. The finest shades in volume and expression can thusbe obtained by the use of only one hand.

The circuit shown in Fig. l is that of an instruthough it is possible tomove the whole range up and down by means of the potentiometer P-'-1,the frequency relations of the notes to each other determined by theresistors R1 to Rn remain constant for a practically unlimited time sothat under normal circumstances no retuning will be necessary.

For special purposes, orchestra work for example, it may be advantageousto tune the individual notes of the instrument. The simplest expedientwould be to make the resistors R-l to R-n variable. These resistances,however, are of the order of 100,000 ohms and adiustable'resistors ofthis type are not only unreliable but are at the sametime ratherexpensive. A practical arrangement for tuning every note independentlyis shown in Fig. 2. This arrangement contemplates a circuit which isnearly identical with the one shown in Fig- 1. The difference is that inFig. 1 all the keys when depressed, make contact with the same contactwire F; which has the potential of the slide arm'P1. On the other handin Fig. 2 a separate current source B-'-1 is provided across which anumber of wire wound potentiometers P--l to P--n are connected, one forevery key. It is easily seen that by means of J-l toJ-n, the

working voltage of each key can be individually adjusted and thm thenote produced thereby can be varied within necessary limits. Generally avoltage of about 2-3 volts is sumcient to give a tuning range of 1 or 2tones up or down.

In the vibrato arrangement illustrated in Fig. 1 a small condenser 0-2is alternately connected to 0-1 causing a little variation of thefrequencies produced. Of course, the pitch jumps from one frequency tothe other. In contrast to the foregoing is the case of the vibrato'oi'the string instruments where the finger of the operator is vibrated onthe strings with the result that a continuous transition occurs betweentwo slightly different pitches. In Fig. 3 a modification of the vibratoarrangement is shown which permits a continuous variation of thecapacity of the tremolo condenser and thus of the frequency of theoscillations. I

Reference characters H-'-l and H-2 designate two brass plates which areprovided with mica insulation between them to form a variable condenserof very low capacity. Plate H-1 is a strip of spring brass with a buttonB-u fastened at the one extremity. When the button is vibrated by thehand of the operator, the capacity of'this small condenser will bealternately increased and decreased. If this condenser is wired in thesame way as 0-2 shown in Fig. 1, it is possible to obtain a perfectimitation of the continuous vibrato of the string instruments or of thehuman voice.

The speed of the vibrato variations of the fre- Cl, resistance R-1,sound producing contrivance L, a fixed resistance R-a: of adequatevalue, (say iii-40,000 ohms). The circuit II (G-2, 0-2, R--2) isidentical with I and the only difference is that a large condenser andhigh resistance are used to give a very low frequency of a fewoscillations a second. Every time when G -2 is lighted, there will be asmall additional drop of voltage through the resistance R-l so thattheworking voltage'oi circuit I will be di minished. The result will bethat the voltage and consequently the frequency in circuit I will besubiect'to small fluctuations in rhythm with the slow oscillations incircuit II. In other words, the desired efiect can be obtained with theaforesaid arrangement.

Many interesting refinements are possible also in connection with thebanjo effect. In Fig. 5 the familiar circuit containing current sourceB, glow-discharge lamp G-1, condenser CL'resistors R1 to R-n andinterrupter A with the contacts d-l and d,-2 can be seen again. The highcapacity condenser Cgc (2-10 microfarads) is connected across currentsource 13, but the connection is interrupted when moving A. In thelatter case the glow-discharge lamp issupplied with current from Cx, butof course its charge being quicklyexhausted, the electromotive force inthe circuit is gradually decreased and, in consequence ofithis decrease,the frequency of the oscillations produced will be graduaily decreaseduntil contact is made again at d-l or d--2. This arrangement produces anote which-starts from one frequency which becomes quickly lower andfinally returns to the original frequency. This very curious and uniquequality when used discriminately gives interesting imitations of toneeffects obtained by strings plucked or hit by various mechanical means.

transformer T in Fig. l, which is to be connected in the output circuitof the oscillator. Transformer T--1 has one primary 19-0" and threesecondaries 8-10; 8-20; 8-30 constituting 3 different circuits, I, II,and III, each of which has a separate tone control switch Bl0, S 20,S-30, connecting difierent capacities 0-10, 0-11; C20; 0-21, C; C--3l,inductances and. resistors or combinations thereof across the circuit.In this manner the original quality may be modified by suppressing orstressing the higher harmonics. Transformer T2 is an output transformerwith three primaries P-lO; P-20; P-30 and one common secondary windingS-e, which recombines these three different qualities and leads them tothe common. amplifier and the sound producing contrivance. Obviouslythis arrangement is not limited to three qualities and can be subject tomany different modifications. The shunt condensers,

resistors, etc., cause considerable losses in energy so that itisadvisable to provide at least one stage of audio frequencyamplification separately for each tone color. Although the circuitindicated in Fig. 10 is perfectly practical, better results and tonequalities can be obtained if the circuits carrying the different tonequalities (I, II, III) are amplified separately and connected toindividual sound producing contrivances, and not recombined into onecommon output circuit as indicated by T2 in Fig. 10.

Not only the glow-discharge lamp oscillator but practically allelectrical musical instruments produce continuous notes, having aboutthe same volume as long as they are sounded. The reason for this is that.all electrical musical instruments produce undamped oscillations. Incontrast to the foregoing notes, a group-of known musical instrumentsand among them the most popular the piano produce damped oscillations, anote struck on the piano rapidly decreases in volume and fades awaycompletely after a while. Of course, the electrical imitation of thecharacteristic piano quality is of very great practical importance. Forproducing this effect, it is-possible to use volume controls across theoutput of the instrument, which when controlled by mechanical meansdecrease the volume of every note a short time after the correspondingkey has been depressed. A much better arrangement is shown in Fig. 9which is based upon purely electrical processes. In this arrangementbetween the output of the oscillator (producing the electricaloscillations of musical frequency) and the amplifier proper, there is anintermediate amplifier tube N arranged, the amplification factor ofwhich canbe influenced for example by varying the plate voltage;

Every key of the instrument apart from the contacts K-11. and F forconnecting the oscillator (glow-discharge lamp, etc., see Fig. 1) to therest of the circuit, is arranged to have another set of contacts dl andd--2 fixed onone extremity of the key. Every time the key is depressed,the contact is closed but only for a very short time because dl willpass over d2 and will touch it only for a moment. This momentarycontact, however, is suflicient to charge up the large fixed condenserC:r (5-20 microfarads) from the current source B. At the same timecontacts Kn and F will be closed and will start the musical oscillationsof the desired pitch. The plate potential of the amplifier tube N willbe supplied from the condenser C:z: but of course the current supplybeing shut 'off, the voltage will decrease very quickly until the chargein the condenser is completely exhausted. This means of course that theamplification of the tube and thus the volume will also decrease from amaximum to zero within a short time. The duration in other words, thedamping of the notes thus produced can be adjusted for example by.varying the capacity C-:n, adding C-y or Cz by means of the switch 8.Obviously the same results can be achieved in many other ways thanbyva'rying the plate voltage of N. In many cases it might be moreadvantageous to change the grid bias or filament of the-tube, some ofthe modern tubes having more than one grid, bing especially adapted forthis.

The possibilities for producing different tone colors are by no meansexhausted by the methods described hereinabove many'variations andcombinations suggest themselves to those familiar with-the art.

As is the case with every musical instrument 7 time.

If the elements are of good quality and the improvements describedherein are made use of, the glow-discharge lamp will produceoscillations of a remarkable stability. Apart from the electromotiveforce, the capacity and resistance in the glow-discharge lamp circuit,the frequency also depends on the critical lighting and extinctionvoltages of the lamp. This in turn is slightly changed when theelectrodes of the lamp are 11- luminated by an external source of light.The illumination facilitates the emission of negative electrons from thecathode and lowers the resistance of the lamp, as is the case with thephoto electric cells. For this reason it is advisable to cover theglow-discharge lamp with an opaque shield'which if made of metal will atthe same time protect the lamp against outside electrical and magneticfields.

Fig. 11 shows an example of a shield SH covering the glow-discharge lampG and fastened to the base of the lamp SO which is made of an opaque,non-transparent material. The wire connection at the top of the shield,of course, only functions in the event that the shield is metallic andcan be used toconnect the shield to a point of constant potential.

Experience also shows that a constant potential should be maintained onthe electrodes of the lamp in order to-obtain maximum stability. Inother words, the circuit; lampcurrent sourceand fixed condenser, shouldalways be closed even when the instrument is not used. The exact reasonsfor this are not yet entirely clear and have not been established. Veryprobably the tube is oscillating at an extremely slow rate, (oneoscillation every 10-15 minutes) even when no resistance is connectedacross the condenser, because the insulation resistance of the pitchcondenser (C1; Fig. 1) is never infinite and represents an extremelyhigh resistance across the condenser. Thus the conditions for theproduction of oscillations arefulfilled even when no one of the keys isdepressed. Very probably these slow oscillations maintain an equilibriumin the arrangement of gas ions and electrons favorable to the stabilityof the oscillations.

In consequence of this the on--ofl' switch of the instrument has to bearranged so as not to interrupt the main circuit of the oscillator butnevertheless to stop the production of oscillations. This condition isfulfilled in the circuit depicted in Fig. l. The switch S-.3 interruptsone side of the potentiometer P-l, 8-2 interrupts the common lead of theresistors F, but the main circuit is left undisturbed. S-2 and 8-3 maybe united in the same two circuit switch so that they are always workedsimultaneously.

Reference has been made several times to the' circumstance that thefrequency of the glowdischarge lamp oscillator depends principally onthe electromotive force, the/capacity and the resistance in the circuit.In consequence of this the same frequency can be; produced by verydiiIerent values of these, as for instance, by a larger capacity and lowresistance and vice versa. The output (volume), however, is by no meansidentical under these different conditions; and appears to be larger,the greater the capacity of the condenser. This gives an excellentpossibility to produce uniform volume for widely difin the usual manner.

ferent frequencies of the musical range, this being especially importantwhen a great number of glow-discharge lamp oscillators are used. All

that is necessary is to use condensers of the same capacity in each ofthe circuits and to obtain the desired differences in pitch forinstance, by means of different resistors. This condition is fulfilledin Fig. l where C1 is common for the whole range and only the resistancein circuit is varied by depressing the different keys.

The oscillations produced by the glow-discharge lamp oscillator needgenerally to be amplified in order to obtain the necessary volume in thesound producing contrivance. The method of transferring the energy fromthe oscillator to the ampliiier is very important. The coupling usedshould be extremely loose, otherwise there will be a reaction from theamplifier to the oscillator changing the impedance and the frequencyresponse of the circuit. As a result'of this the instrument might be intune with a certain amplifier and entirely out of tune with another. Thefact that the oscillations of the glow-discharge lamp are accompanied byperiodic emissions of light from the electrodes can be advantageouslyused for coupling the oscillator to the amplifier without any electricalconnection existing between them (Fig. 8).

Oscillations are set up' in the circuit B, G, C, R p In the proximity ofthe glow-discharge lamp G is situated the photo electric cell Ph whichis illuminated by every discharge of G. The weak photo electric currentsset up in Ph due to the periodic discharges in the lamp G are amplifiedand converted into sound by the sound producing contrivance L. Everyelectric connection between the oscillator and the amplifier has beenthus eliminated, giving an absolute freedom from reaction from theamplifier, or from the transfer of contact making and breaking clicksfrom the oscillator. Obviouslyseveral photo electric cells can beilluminated by the same glow-discharge lamp and vice versa theoscillations produced by a multiplicity of glow discharge lamps can bepicked up by one photo electric cell. Filters, diaphragms and the likearranged as D between G and Ph can beused for making variations in thetransfer of light energy for changing volume, tone color, etc. a

For the amplification of the electrical oscillations of musicalfrequency as produced by theglow-discharge lamp oscillator any audiofrequency amplifier can be used, or the audio-frequency part of anyradio receiver. Eventually the generator of musical frequencies can beused,.

first to modulate a small radio-frequency oscillator; the instrument andthe radio-frequency generator together produce a radio-frequency currentmodulated by the musical frequencies much in the same way as is done ata radio transmitting station. The resulting signal can now be impressedupon the radio receiver either by wireless (having the set in proximityof the oscillator) or by means of a wire connection between the outputof the audio-radio oscillator combination and the aerial-ground posts ofthe radio receiver.

In the left part of the drawings the usual arrangement of aglow-discharge lamp electrical musical instrument consisting ofglow-discharge lamp, G, condenser, C, sourcev of current, B, a pluralityof resistors, Rl to Rn with associated switching keys, K--1 to K- -n canbe seen.

The middle part of the drawings shows argenerator of radio-frequencyoscillations, the audion tube OS is arranged in one of the conventionalcircuits, oscillations set up in the plate circuit of the tube arepartly fed back to the oscillatory circuit on the grid, partlytransferred to the aerial AE-l. These radio frequency oscillations aremodulated by the output of the musical instrument IN, the output beingcoupled to the grid circuit of 08 through the transformer TR, andthereby varying the grid bias of the oscillator. In consequenceof this,in the aerial AE-l a modulated radio frequency current will be existingwhen the electrical musical instrument is played. This signal will bepickedup by the aerial AE-2 of the radio receiver, RE, arranged in theproximity of AE-l, and the sound-producing means L will emit soundcorresponding to the switching keys operated in the electrical musicalinstrument. Obviously any other electrical musical instrument can besubstituted in the place of the instrument of the glow-discharge lamptype; and like-wise any of the known and various methods of generatinghigh frequency currents and modulating same by an audio frequencycurrent can be used. In order to insure maximum efliciency, theoscillator 08 and the receiver RE have to be tuned to the samewave-length. The advantage of this method is that any radio receiver,without any change whatever can be used for the amplification, that boththe radio and the audio-frequency amplification oi the receiver are madeuse of, and that in addition a wire-connection between the instrumentand the amplifier (in this case the radio receiver) is not absolutelynecessary.

It will be observed that the present invention provides an electricalmusical instrument in which sounds are produced by means of electricaloscillations produced in oscillating circuits which are controlled tovary the sound produced,

1. An electrical musical instrument comprising a main electrical-circuitcontaining a source of current, a glow-discharge lamp and a condenser inseries with said source of current; an auxiliary circuit operativelyconnected with said main circuit containing a plurality of resistancesin series, a switching key for each of. the said resistances locatedbetween each common point of any two adjoining resistances and one sideof the condenser, said key being normally open to dis-Y connect theresistances from the main circuit and being capable of actuation forshunting a plurality of said series resistances acrosss'aid condenserthereby completing the main circuit and causing current to flow throughsaid lamp; and sound-producing means connected in said main circuit andcapable of emitting sound, the pitch of'the emitted sound being thehighest when one resistance is operating and being the lowest when ,311of the series resistances are operating and intermediate when aplurality of resistances are operating.

2. An electrical musical instrument comprising a main electrical circuitcontaining a source of current, a glow-discharge lamp, a condenser andances located between each common point of two to flow through saidlamp; and sound producing means connected to the secondary winding ofsaid transformer and being capable of emitting sound of a differentpitch for every switching key operated, the sound being the highest whenonly one resistance is connected across the condenser and being thelowest when all the series resistances are connected across thecondenser.

3'. An electrical musical instrument comprising a main electricalcircuit containing a source of current, a glow-discharge lamp, acondenser and the primary winding of a transformer, all in series withsaid source of current; anauxiliary circuit operatively connected withsaid main circuit containing a plurality of resistances in series, a

, switching key for each oi. the said resistances located between eachcommon point of any two adjoining resistances and one side of thecondenser, said key being normally open to disconnect the resistancefrom the main circuit and being capable of actuation for shunting aplurality of said series resistances across said condenser and therebycompleting the main circuit and for causingcurrent to-flow through saidlamp; means located in the main circuit for varying the voltage of thesource of current; sound-producing means connected to the secondary ofthe transformer and being capable of emitting sound of different pitchfor every switching key operated, the pitch of each musical note varyingwith a variation of the voltage of the source of current and the musicalintervals between the various notes remaining substantially constant. I

4. An electrical musical instrument comprising a main electricalcircuit-containing a source of current, means for adjusting the voltageof said source of current, a glow-discharge lamp, 9. condenser and theprimary winding of a transformer,

all in series with said source of current; an auxiliary circuitoperatively connected with said main circuit containing a plurality ofresistances in series, a switching key for each of the saidresistadjoining resistances and one side of the condenser, said keybeing normally open to disconnect the resistance from the main circuitand being capable of actuation for shunting a plurality of said seriesresistances across said condenser and for causing current to flowthrough said lamp, a second auxiliary circuit containing a condenser andan electrical contact capable of connecting and disconnecting saidcondenser across the main circuit condenser thereby causing smallvariations ofthe capacity thereof; sound-producing means operativelyassociated with the secondary of the transformer and being capable ofemitting sound of difierent pitch for every switching key operated, thepitch of the emitted sound being varied when the capacity of the maincircuit condenser is varied by connecting the auxiliary circuitcondenser thereto.

5. An electrical musical instrument comprising a main electrical circuitcontaining a source of current, means for adjusting the voltage of saidsource or current, a glow-discharge iamp,-a condenser and the-primary ofa transformer, all in series with said source of current; an auxiliarycircuit operatively connected with saidmain circuit containing aplurality of resistances in series, a switching key for each of thesaidresistances located between each common point of two adjoining.resistances and one side of. the condenser, said key being-ncrmallyopen to disconnect the resistance from the main circuit and-beingcapable of actuation for shunting a plurality means operativelyassociated with the transformer and being capable of emitting sound ofdifferent pitch for every switching key operated, the emitted soundstarting and stopping in rapid succession when the main circuitinterrupter is operated.

6. Anelectrical musical instrument comprisinga main electrical circuitcontainmg a source of current, means for adjusting the voltage of saidsource of current, a glow-discharge lamp, a condenser and the primarywinding of a transformer, all in series with said source of current; anauxiliary circuit operatively connected with said main circuitcontaining a plurality of resistances in series, a switching key foreach of the said resistanceslocatedbetween each common point of twoadjoining resistances and one side of the condenser, said key beingnormally open to disconnect the resistance from the main circuit andbeing capable of actuation for shunting a plurality of said seriesresistances'across said condenser and for causing current to flowthrough said lamp; a second auxiliary circuit containing a condenser andan elec-.

trical contact capable of connecting and disconnecting said condenseracross the main circuit condenser; a switch arranged between the secondauxiliary circuit and the main circuit permitting to switch over saidelectrical contact in series with the main circuit for rapidly openingand closing same; sound-producing means operatively associated with thetransformer and being capable of emitting sound of different pitch foreveryv switching key operated, the pitch of said emitted sound beingvaried when said electric contact is'connected and operated inthe'second auxiliary circult, and the emitted sound starting andstoppingv in rapid succession when said electric contact is operated inthe main circuit.

7. An electrical musical instrument comprising a main electrical circuitcontaining a source of current, means for adjusting the voltage of saidsource of cur'rent,,a glow-discharge lamp, a condenser and the primarywinding of a transformer, all in series with said source of current; amultiplicity of impedances capable of being selectively connected acrossprimary or secondary winding'of said transformer for changing frequencyresponse of'same; an auxiliary circuit operatively connected with saidmain circuit containing a plurality of resistances in series, aswitching key for each of the said resistances located between eachcommon point of two adjoining resistances and one side of the condenser,said key being normally open to disconnect the resistances from the maincircuit and being capable of actuationfor shunting a plurality of saidseries resistances across said condenser and for causing current'to flowthrough said lamp; a second auxiliary circuit containing a condenser andan electrical contact capable of connecting and disconnecting saidcondenser across the main circuit condenser; a switch situated betweenthe second auxiliary circuit and the main circuit'permitting to switchover said electrical contact in series with the main circuit-for rapidlyopening and closing same; sound-producing means operativel'y associatedwith the transformer; a

volume-control device intermediary to the transformer and thesound-producing means controlling the transfer of electrical energyto'same; said sound producing means being capable of emitting a sound ofdifferent pitch for every switching key operated, the tone color of theemitted sound varying when the impedance across the transformer windingis varied; and the volume of the emitted sound varying when theadjustment of said volume control device is varied.

8. An electrical musical instrument comprising a main electrical circuitcontaining a source of current, means for adjusting the voltage of saidsource ofcurrent, a glow-discharge lamp, a condenser and the primarywinding of a transformer, all in series with said source of current; amultiplicity of impedances capable of being selectively connected acrossprimary or secondary winding of said transformer; an auxiliary circuitoperatively connected with said main circuit containing a plurality ofresistances in series, a switching key for each of these resistanceslocated between each common point of two adjoining resistances and oneside of the condenser, said key being normally open to disconnect theresistance from the main circuit and being capable of actuation forshunting a plurality of said series resistances across said condenser; asecond auxiliary circuit containing a. condenser and an electrol deviceintermediary to the transformer and the sound-producing means; and acontrol lever movable in two diiferent directions, said levercontrolling the aforesaid volume-control when moved in the onedirection. and operating the aforesaid i(Geilectrical contact when movedin the otherdirec- 9. An electrical musical instrument comprising a mainelectrical circuit containing a source of current, a glow dischargelamp, a condenser and 'the primary winding of a transformer all inseries with said source of current; an auxiliary'circuit operativelyconnected with said main circuit containing a plurality of resistancesin series, a switching key for each of the said resistances locatedbetween each common point of two adjoining resistances and one side ofthe condenser, said key being normally open to disconnect the resistancefrom the main circuitandbeing capable of actuation for shunting aplurality of said series resistances across said condenser and forcausing current to flow through said lamp, an-

other condenser being capable of control for continuous variationconnected across the main circuit condenser capable of changing theresultant capacity of both condensers continuously; sound-producingmeans operatively associated with the secondary of the transformer andbeing capable of emitting sound of diiferent pitch for every switchingkey operated, the pitch of said emitted sound being continuously variedwhen the capacity of the condenser associated with the main circuitcondenser is continuously varied.

10. An electrical musical instrument comprising a main electricalcircuit containing a source of current, a glow-discharge lamp, acondenser and the primary winding of a transformer all in series withsaid source of current, an auxiliary circuit operatively connected withsaid main circuit containing a plurality of resistances in series, aswitching key for each of the said resistances located between eachcommon point of any two adjoining resistances and one side of thecondenser, said key being normally open to disconnect the resistancesfrom the main circuit and being capable of actuationfor shunting aplurality of said series resistances across said condenser and causingcurrent to flow through said lamp; an onofi switch capable ofinterrupting the auxiliary circuit thereby making inoperative theswitching keys and at the same time leaving the main circuitundisturbed; and sound-producing means operatively associated with thetransformer and being capable of emitting sound of a different pitch foreveryswitching key operated when the aforesaid on-off switch iscompleting the auxiliary circuit and being inoperative when by saidswitch the auxiliary circuit is interrupted.

11. An electrical musical instrument comprising a circuit containingaglow-discharge lamp, a condenser, a resistance and a source of current;means for producing oscillating electrical currents in said circuit;control means for said oscillating producing means for varying thefrequency of the oscillations and including a plurality or manuallyoperative elements; and means for collectively varying the effect of themanually operative elements.

12. An electrical musical instrument comprising a plurality of circuitscontaining glow-discharge lamps, condensers, resistances and sources ofcurrent; means for producing oscillating electrical currents in saidcircuits; control means for said oscillating producing means for varyingthe frequency of the oscillations and including a plurality of manuallyoperative elements; means for collectively varying the eifect' of themanually operative elements; and means for regulating the pitch.

NICHOLAS LANGER.

